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dimanche 25 juin 2017

Stars may all be born in pairs and lose their siblings later

A mysterious, unseen, planetary object with a mass somewhere between that of Mars and Earth may be lurking in the outer reaches of our solar system, according to new research.
Scientists at the University of Arizona's Lunar and Planetary Laboratory (LPL) put forward evidence that this unknown “planetary mass object” may explain why the plane of the solar system is warped in the outer reaches of the Kuiper Belt.

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Stars may all be born in pairs and lose their siblings later

All stars might form in multiple-star systems, and simply drift apart -
or fling their partners away - over time.

A cloud of gas and young stars in the Perseus molecular cloud may be revealing a strange truth to the universe: most, if not all, stars are born in pairs. This means that somewhere out there, the Sun has a lost companion — and it may be one of several known stars.

Essentially, all stars form in molecular clouds. In the Perseus observations, nearly all of these stars were gravitationally bound. This may be a requirement of protostars — the egg-like objects could require a common center of gravity with a companion to accumulate mass. The dense cores then use leftover material to form more stars, continuing the process.

So why doesn’t the Sun have a binary companion (well, depending on who you ask)? It seems that 60 percent of stars shed their binary sister over time, gaining a wider distance from their partner until they are gravitationally severed. They also may not all have the same symmetry with regard to mass, meaning that some former companions could be brown dwarfs cast out by larger stars.

The authors of the paper, accepted in the Monthly Notices of the Royal Astronomical Society, say more work is needed to confirm their hypothesis. But if it’s true, the hunt may be on for the companion the Sun once had. Source : ASTRONOMYmagazine®